Dynamic NAT is one of the implementations of #202206281817 that maps public address from pool to private address when it is available. Such assignment will only last for a single communication session, which means it will become available to the other local network devices once the current device went down. This mechanism preserves address space. That being said, it can still run out of public address if there are too many devices request for the assignment.
It is good for security since the private address is not visible to the outside world.